Designing a cement slurry with a Young&#39;s modulus requirement

ABSTRACT

A method of generating a wellbore treatment fluid comprising: obtaining a target Young&#39;s modulus; calculating a compressive strength requirement from a correlation comprising compressive strength and Young&#39;s modulus using the target Young&#39;s modulus as an input; classifying a plurality of solid particulates using correlations; calculating a reactive index and/or a water requirement for at least one of the solid particulates; and selecting two or more solid particulates from the plurality of solid particulates to create a wellbore treatment fluid, wherein two or more solid particulates are selected such that when the wellbore treatment fluid is prepared and set, the set wellbore treatment fluid has a 24 hour compressive strength greater than or equal to the compressive strength requirement.

BACKGROUND

In well cementing, such as well construction and remedial cementing,cement compositions are commonly utilized. Cement compositions may beused in a variety of subterranean applications. For example, insubterranean well construction, a pipe string (e.g., casing, liners,expandable tubulars, etc.) may be run into a well bore and cemented inplace. The process of cementing the pipe string in place is commonlyreferred to as “primary cementing.” In a typical primary cementingmethod, a cement composition may be pumped into an annulus between thewalls of the well bore and the exterior surface of the pipe stringdisposed therein. The cement composition may set in the annular space,thereby forming an annular sheath of hardened, substantially impermeablecement (i.e., a cement sheath) that may support and position the pipestring in the well bore and may bond the exterior surface of the pipestring to the subterranean formation. Among other things, the cementsheath surrounding the pipe string functions to prevent the migration offluids in the annulus, as well as protecting the pipe string fromcorrosion. Cement compositions also may be used in remedial cementingmethods, for example, to seal cracks or holes in pipe strings or cementsheaths, to seal highly permeable formation zones or fractures, to placea cement plug, and the like.

A particular challenge in well cementing is the development ofsatisfactory mechanical properties in a cement composition within areasonable time period after placement in the subterranean formation.Oftentimes several cement compositions with varying additives are testedto see if they meet the material engineering requirements for aparticular well. The process of selecting the components of the cementcomposition are usually done by a best guess approach by utilizingprevious slurries and modifying them until a satisfactory solution isreached. The process may be time consuming and the resulting slurry maybe expensive. Furthermore, the cement components available in any oneparticular region may vary in composition from those of another regionthereby further complicating the process of selecting a correct slurry.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe present invention, and should not be used to limit or define theinvention.

FIG. 1 is a chart showing simulated results for compressive strengthindex calculations.

FIG. 2 is a chart showing simulated results for compressive strengthindex calculations.

FIG. 3 is a schematic illustration of an example system for analyzingcement components.

FIG. 4 is a schematic illustration of an example system for generatingcement compositions.

FIG. 5 is a schematic illustration of showing introduction of a cementcomposition into a wellbore.

FIG. 6 is a graph of predicted Young's modulus versus observed Young'smodulus for a cement composition.

FIG. 7 is a graph of predicted Young's modulus versus observed Young'smodulus for a cement composition.

DETAILED DESCRIPTION

The present disclosure may generally relate to cementing methods andsystems. Provided herein are methods that may include identifying andcategorizing silica sources, cements, and other materials based onphysiochemical properties. In some examples, the silica sources may beconsidered inorganic particles. The inorganic particles may or may notcomprise silica and may comprise other minerals such as alumina andother oxides. The physiochemical properties of each cement component ofa cement composition may affect the final set mechanical properties ofthe slurry such as Young's modulus as well as the dynamic or time basedproperties such as mixability, rheology, viscosity, and others. Everycement component may affect one or more of the properties mentioned,sometimes unpredictably. For example, a locally sourced fly ash may beadded to a cement composition. The added fly ash may increase thecompressive strength of the cement composition and may have no effect onfor example, the thickening time of the cement composition. In anotherregion, a locally sourced fly ash may also increase the compressivestrength of the cement composition but may also increase the thickeningtime. The unpredictable behavior of a cement composition may not berealized until multiple lab tests have been performed.

Furthermore, designing a cement composition generally requires certaintarget parameters to be achieved, such as compressive strength in thefinal set cement. Whether by regulatory requirements or customerrequirements compressive strength may be a strong determining factor ofwhether a certain cement composition performs are required and will beselected to be pumped into a wellbore. A cement composition which isdesigned with compressive strength as a main design requirement mayresult in a cement composition that is overdesigned with respect tocompressive strength which may result in higher cost of goods sold(“COGS”) than may be necessary. Additionally, a cement with a relativelyhigh compressive strength may result in relatively less ductility in thefinal cement sheath. Generally speaking, ductility increases as Young'sModulus decreases. Thus, exceeding the necessary compressive strengthrequirement of a cement sheath, may result in premature failure of thecement sheath due to lower ductility, potentially requiring additionalremedial cement work to repair. Cement compositions designed primarilywith compressive strength may result in additional additives being usedwhich in turn may result in a higher cost of the cement composition.

A method presented herein may comprise designing a cement compositionwith Young's modulus as a design requirement. Various chemical additivesmay be used to modulate the Young's modulus of a particular cementcomposition. These chemical additives may be costly, may not becompatible with all wellbores, and may result in additional equipmentcost associated with transportation and storage among other potentiallynegatives. Young's Modulus may also be modulated by changing thecomposition of the cement such as by increasing or reducing a particularcementitious component. Generally, designing a well bore cement slurryfor Young's modulus can increase cost and time required to design andtest. However, following techniques disclosed herein can minimize theCOGS and also minimize the time required to develop appropriate cementslurry formulations.

The method may be combined with other slurry design processes to selectthe cementitious components that produce the required Young's modulusand by extension, design a cement composition with a selectedcompressive strength. The method may correlate a Young's modulus of aset cement from compressive strength and density of the cementcomposition for a wide range of temperatures, densities, and compositionportfolios of bulk blends of cements.

The cement compositions generally may comprise water and a cementadditive. The cement additive may comprise two or more cementcomponents, which may be dry blended to form the cement additive priorto combination with the water. Alternatively, the cement components maynot be combined until the mixture is combined with the water. The cementcomponents may generally be described as alkali soluble. A cementcomposition may comprise water and a cement additive, wherein the cementadditive may comprise one or more of hydraulic cement, cement kiln dust,and a natural pozzolan. As described in more detail herein, the cementcompositions may be foamed and/or extended as desired by those ofordinary skill in the art.

The cement compositions may have a density suitable for a particularapplication. The cement compositions may have any suitable density,including, but not limited to, in the range of about 8 pounds per gallon(“ppg”) to about 16 ppg (1 g/cm³ to 1.9 g/cm³). In the foamed examples,the cement compositions may have a density in the range of about 8 ppgto about 13 ppg (1 g/cm³ to 1.6 g/cm³) (or even lower). It should beunderstood that the present techniques should also encompass the use ofcement compositions with densities outside the specific ranges disclosedherein.

The water used in the cement compositions may include, for example,freshwater, saltwater (e.g., water containing one or more saltsdissolved therein), brine (e.g., saturated saltwater produced fromsubterranean formations), seawater, or combinations thereof. Generally,the water may be from any source, provided that it does not contain anexcess of compounds that may undesirably affect other components in thecement composition. The water may be included in an amount sufficient toform a pumpable slurry. The water may be included in the cementcompositions in any suitable range, including, but not limited to, inthe range of about 40% to about 200% by weight of the cement additive(“bwoc”). In some examples, the water may be included in an amount inthe range of about 40% to about 150% bwoc.

The cement additive may comprise two or more cement components. One ofthe cement components may comprise a hydraulic cement. A variety ofhydraulic cements may be utilized in accordance with the presentdisclosure, including, but not limited to, those comprising calcium,aluminum, silicon, oxygen, iron, and/or sulfur, which set and harden byreaction with water. Suitable hydraulic cements may include Portlandcements, gypsum, and high alumina content cements, among others.Portland cements that are suited for use in the present disclosure maybe classified as Classes A, C, G, and H cements according to AmericanPetroleum Institute, API Specification for Materials and Testing forWell Cements, API Specification 10, Fifth Ed., Jul. 1, 1990. Inaddition, in some examples, cements suitable for use in the presentinvention may be classified as ASTM Type I, II, or III. Cementcompositions that may be considered “low Portland” may be designed byuse of the techniques disclosed herein.

Where present, the hydraulic cement generally may be included in thecement compositions in an amount sufficient to provide the desiredcompressive strength, density, and/or cost. The hydraulic cement may bepresent in the cement compositions in any suitable amount, including,but not limited to, in the range of about 0% to about 99% bwoc. In someexamples the hydraulic cement may be present in an amount rangingbetween any of and/or including any of about 1%, about 5%, about 10%,about 20%, about 40%, about 60%, about 80%, or about 90% bwoc. Cementcomposition that are considered “low Portland” may be used, in that thePortland cement (where used) may be present in the cement composition inan amount of about 40% or less bwoc and, alternatively, about 10% orless. In addition, the cement compositions may also be designed that arefree (or essentially free) of Portland cement. Those of ordinary skillin the art, with the benefit of this disclosure, should be able toselect an appropriate amount of hydraulic cement for a particularapplication.

In addition to hydraulic cement, additional cement components may beused that can be considered alkali soluble. A cement component isconsidered alkali soluble where it is at least partially soluble in anaqueous solution of pH 7.0 or greater. Certain of the alkali solublecement components may comprise a geopolymer cement, which may comprisean aluminosilicate source, a metal silicate source, and an activator.The geopolymer cement may react to form a geopolymer. A geopolymer is aninorganic polymer that forms long-range, covalently bonded,non-crystalline networks. Geopolymers may be formed by chemicaldissolution and subsequent re-condensation of various aluminosilicatesand silicates to form a 3D-network or three-dimensional mineral polymer.

The activator for the geopolymer cement may include, but is not limitedto, metal hydroxides chloride salts such as KCl, CaCl₂, NaCl, carbonatessuch as Na₂CO₃, silicates such as sodium silicate, aluminates such assodium aluminate, and ammonium hydroxide.

The aluminosilicate source for the geopolymer cement may comprise anysuitable aluminosilicate. Aluminosilicate is a mineral comprisingaluminum, silicon, and oxygen, plus counter-cations. There arepotentially hundreds of suitable minerals that may be an aluminosilicatesource in that they may comprise aluminosilicate minerals. Eachaluminosilicate source may potentially be used in a particular case ifthe specific properties, such as composition, may be known. Someminerals such as andalusite, kyanite, and sillimanite are naturallyoccurring aluminosilicate sources that have the same composition,Al₂SiO₅, but differ in crystal structure. Each mineral andalusite,kyanite, or sillimanite may react more or less quickly and to differentextents at the same temperature and pressure due to the differingcrystal structures. Other suitable aluminosilicate sources may include,but are not limited to, calcined clays, partially calcined clays,kaolinite clays, lateritic clays, illite clays, volcanic rocks, minetailings, blast furnace slag, and coal fly ash.

The metal silicate source for the geopolymer cement may comprise anysuitable metal silicate. A silicate is a compound containing an anionicsilicon compound. Some examples of a silicate include the orthosilicateanion also known as silicon tetroxide anion, SiO₄ ⁴⁻ as well ashexafluorosilicate [SiF₆]²⁻. Other common silicates include cyclic andsingle chain silicates which may have the general formula[SiO_(2+n)]^(2n−) and sheet-forming silicates ([SiO_(2.5)]⁻)_(n). Eachsilicate example may have one or more metal cations associated with eachsilicate molecule. Some suitable metal silicate sources and may include,without limitation, sodium silicate, magnesium silicate, and potassiumsilicate.

Where present, the geopolymer cement generally may be included in thecement compositions in an amount sufficient to provide the desiredcompressive strength, density, young's modulus, and/or cost. Thegeopolymer cement may be present in the cement compositions any suitableamount, including, but not limited to, in an amount in the range ofabout 0% to about 99% bwoc. In some examples the geopolymer cement maybe present in an amount ranging between any of and/or including any ofabout 1%, about 5%, about 10%, about 20%, about 40%, about 60%, about80%, or about 90% bwoc. Those of ordinary skill in the art, with thebenefit of this disclosure, should be able to select an appropriateamount of geopolymer cement for a particular application.

Additional cement components that are alkali soluble may be considered asilica source. As used herein, silica has the plain and ordinary meaningof silicon dioxide (SiO₂). By inclusion of the silica source, adifferent path may be used to arrive at a similar product as fromPortland cement. For example, a pozzolanic reaction may be inducedwherein silicic acid (H₄SiO₄) and portlandite (Ca(OH)₂ react to form acement product (calcium silicate hydrate). If other compounds, such as,aluminate, are present in the silica source, additional reactions mayoccur to form additional cement products, such as calcium aluminatehydrates. Additionally, alumina may be present in the silica source. Asused herein, alumina is understood to have the plain and ordinarymeaning of aluminum oxide (Al₂O₃). Calcium hydroxide necessary for thereaction may be provide from other cement components, such as Portlandcement, or may be separately added to the cement composition. Examplesof suitable silica sources may include fly ash, slag, silica fume,crystalline silica, silica flour, cement kiln dust (“CKD”), volcanicrock, perlite, metakaolin, diatomaceous earth, zeolite, shale, andagricultural waste ash (e.g., rice husk ash, sugar cane ash, and bagasseash), among other. Some specific examples of the silica source will bediscussed in more detail below. Where present, the silica sourcegenerally may be included in the cement compositions in an amountsufficient to provide the desired compressive strength, density, and/orcost. The silica source may be present in the cement compositions in anysuitable amount, including, but not limited to an amount in the range ofabout 0% to about 99% bwoc. In some examples the silica source may bepresent in an amount ranging between any of and/or including any ofabout 1%, about 5%, about 10%, about 20%, about 40%, about 60%, about80%, or about 90% bwoc. Those of ordinary skill in the art, with thebenefit of this disclosure, should be able to select an appropriateamount of silica source for a particular application.

An example of a suitable silica source may comprise fly ash. A varietyof fly ash may be suitable, including fly ash classified as Class C andClass F fly ash according to American Petroleum Institute, APISpecification for Materials and Testing for Well Cements, APISpecification 10, Fifth Ed., Jul. 1, 1990. Class C fly ash comprisesboth silica and lime, so it may set to form a hardened mass upon mixingwith water. Class F fly ash generally does not contain a sufficientamount of lime to induce a cementitious reaction, therefore, anadditional source of calcium ions is necessary for a set-delayed cementcomposition comprising Class F fly ash. In some embodiments, lime may bemixed with Class F fly ash in an amount in the range of about 0.1% toabout 100% by weight of the fly ash. In some instances, the lime may behydrated lime. Suitable examples of fly ash include, but are not limitedto, POZMIX® A cement additive, commercially available from HalliburtonEnergy Services, Inc., Houston, Tex.

Amorphous silica may also be present. Amorphous silica may preventstrength retrogression. In general, amorphous silica may not requiretemperatures above 235° F. (112.77° C.) to participate in cementhydrations. Amorphous silica may protect against strength retrogressionand maximize design efficiency by eliminating the need for multipledesigns at different temperatures. Amorphous silica may also replacecrystalline silica in some applications.

Another example of a suitable silica source may comprise slag. Slag isgenerally a by-product in the production of various metals from theircorresponding ores. By way of example, the production of cast iron canproduce slag as a granulated, blast furnace by-product with the slaggenerally comprising the oxidized impurities found in iron ore. Slaggenerally does not contain sufficient basic material, so slag cement maybe used that further may comprise a base to produce a settablecomposition that may react with water to set to form a hardened mass.Examples of suitable sources of bases include, but are not limited to,sodium hydroxide, sodium bicarbonate, sodium carbonate, lime, andcombinations thereof.

Another example of a suitable silica source may comprise CKD. Cementkiln dust or “CKD”, as that term is used herein, refers to a partiallycalcined kiln feed which is removed from the gas stream and collected,for example, in a dust collector during the manufacture of cement.Usually, large quantities of CKD are collected in the production ofcement that are commonly disposed of as waste. Disposal of the CKD aswaste can add undesirable costs to the manufacture of the cement, aswell as the environmental concerns associated with its disposal. CKD isanother component that may be included in examples of the cementcompositions.

Another example of a suitable silica source may comprise volcanic rock.Certain volcanic rocks may exhibit cementitious properties, in that itmay set and harden in the presence of hydrated lime and water. Thevolcanic rock may also be ground, for example. Generally, the volcanicrock may have any particle size distribution as desired for a particularapplication. In certain embodiments, the volcanic rock may have a meanparticle size in a range of from about 1 micron to about 200 microns.The mean particle size corresponds to d50 values as measured by particlesize analyzers such as those manufactured by Malvern Instruments,Worcestershire, United Kingdom. One of ordinary skill in the art, withthe benefit of this disclosure, should be able to select a particle sizefor the volcanic rock suitable for a chosen application.

Another example of a suitable silica source may comprise metakaolin.Generally, metakaolin is a white pozzolan that may be prepared byheating kaolin clay, for example, to temperatures in the range of about1112° F. (600° C.) to about 1472° F. (800° C.).

Another example of a suitable silica source may comprise shale. Amongother things, shale included in the cement compositions may react withexcess lime to form a suitable cementing material, for example, calciumsilicate hydrate. A variety of shales are suitable, including thosecomprising silicon, aluminum, calcium, and/or magnesium. An example of asuitable shale comprises vitrified shale. Generally, the shale may haveany particle size distribution as desired for a particular application.In certain embodiments, the shale may have a particle size distributionin the range of about 37 micrometers to about 4,750 micrometers.

Another example of a suitable silica source may comprise zeolite.Zeolites generally are porous alumino-silicate minerals that may beeither a natural or synthetic material. Synthetic zeolites are based onthe same type of structural cell as natural zeolites, and may comprisealuminosilicate hydrates. As used herein, the term “zeolite” refers toall natural and synthetic forms of zeolite. Examples of zeolites mayinclude, without limitation, mordenite, zsm-5, zeolite x, zeolite y,zeolite a, etc. Furthermore, examples comprising zeolite may comprisezeolite in combination with a cation such as Na⁺, K⁺, Ca²⁺, Mg²⁺, etc.Zeolites comprising cations such as sodium may also provide additionalcation sources to the cement composition as the zeolites dissolve.

The cement compositions may further comprise hydrated lime. As usedherein, the term “hydrated lime” will be understood to mean calciumhydroxide. In some examples, the hydrated lime may be provided asquicklime (calcium oxide) which hydrates when mixed with water to formthe hydrated lime. The hydrated lime may be included in examples of thecement compositions, for example, to form a hydraulic composition withthe silica source. For example, the hydrated lime may be included in asilica source-to-hydrated-lime weight ratio of about 10:1 to about 1:1or a ratio of about 3:1 to about 5:1. Where present, the hydrated limemay be included in the cement compositions in an amount in the range offrom about 10% to about 100% by weight of the silica source, forexample. In some examples, the hydrated lime may be present in an amountranging between any of and/or including any of about 10%, about 20%,about 40%, about 60%, about 80%, or about 100% by weight of the silicasource. One of ordinary skill in the art, with the benefit of thisdisclosure, should recognize the appropriate amount of hydrated lime toinclude for a chosen application.

In some examples, the cement compositions may comprise a calcium sourceother than hydrated lime. In general, calcium and a high pH, for examplea pH of 7.0 or greater, may be needed for certain cementitious reactionsto occur. A potential advantage of hydrated lime may be that calciumions and hydroxide ions are supplied in the same molecule. In anotherexample, the calcium source may be Ca(NO₃)₂ or CaCl₂ with the hydroxidebeing supplied form NaOH or KOH, for example. One of ordinary skillwould understand the alternate calcium source and hydroxide source maybe included in a cement composition in the same way as hydrated lime.For example, the calcium source and hydroxide source may be included ina silica source-to-hydrated-lime weight ratio of about 10:1 to about 1:1or a ratio of about 3:1 to about 5:1. Where present, the alternatecalcium source and hydroxide source may be included in the cementcompositions in an amount in the range of from about 10% to about 100%by weight of the silica source, for example. In some examples, thealternate calcium source and hydroxide source may be present in anamount ranging between any of and/or including any of about 10%, about20%, about 40%, about 60%, about 80%, or about 100% by weight of thesilica source. One of ordinary skill in the art, with the benefit ofthis disclosure, should recognize the appropriate amount of alternatecalcium source and hydroxide source to include for a chosen application.

A target silica lime ratio may be defined and a cement additivecomprising two or more cement components may be identified that meetsthe silica lime ratio. In some examples, the target silica lime ratiomay range from about 80/20 silica to free lime by weight to about 60/40silica to free lime by weight, for example, be about 80/20 silica tofree lime by weight, about 70/30 silica to free lime by weight, or about60/40 silica to free lime by weight. The silica lime ratio may bedetermined by measuring the available silica and lime for a given cementcomponent.

Other additives suitable for use in cementing operations also may beincluded in embodiments of the cement compositions. Examples of suchadditives include, but are not limited to: weighting agents, retarders,accelerators, activators, gas control additives, lightweight additives,gas-generating additives, mechanical-property-enhancing additives,lost-circulation materials, filtration-control additives,fluid-loss-control additives, defoaming agents, foaming agents,transition time modifiers, dispersants, thixotropic additives,suspending agents, and combinations thereof. One of ordinary skill inthe art, with the benefit of this disclosure, should be able to selectan appropriate additive for a particular application.

As mentioned previously, in order to determine if two or more of theaforementioned cement components are compatible, several lab tests maybe run. Additionally, any potential synergistic effects of the cementcomponent may not be known unless several laboratory tests areperformed. Typically, a known cement composition may be first formulatedand tested for properties such as, for example, the 24 hour compressivestrength, fluid loss, and thickening time. Then, varying amounts ofadditives may be added to a fresh batch of cement compositions and thetests are re-run. The results are gathered form each test and compared.A new set of tests may then be run with new concentrations of additives,for example, to adjust properties of the cement composition. The processof testing various additives in varying concentrations may go on forseveral trials until an acceptable cement composition or compositions isformulated. An acceptable cement composition may be one that meetscertain design requirements, such as compressive strength, fluid loss,and thickening time. The cement composition design process may be donein a heuristic manner leading to a cement composition that may have therequired engineering properties but may not be optimized for cost.Additionally, silica sources such as, for example, CKD, have beenpreviously used as either pure fillers or in some examples, reactivecomponents, in Portland based cement compositions. CKD will contribute aportion of silica which requires a portion of lime to react. In methodsof cement composition formulation described above, the heuristic processdoes not take into account the silica to lime ratio of a composition.

The method described herein may reduce or eliminate the heuristic searchfor by a process that identifies a cement additive through a process ofmeasuring and categorizing a variety of cement components referred to asreactivity mapping. Reactivity mapping may generate a correlationbetween properties of inorganic particles. Reactivity mapping maycomprise several steps. One step may comprise measuring the physical andchemical properties of different materials through standardized tests.Another step may comprise categorizing the materials through analysis ofdata collected and the predicted effect on cement slurry properties. Yetanother step may comprise utilizing the data to estimate materialreactivity, improve cement performance, predicting blend mechanicalproperties mathematically based on analytical results, and/or predictslurry density dependence of compressive strength.

Measuring physical and chemical properties of each selected cementcomponent may comprise many laboratory techniques and proceduresincluding, but not limited to, microscopy, spectroscopy, x-raydiffraction, x-ray fluorescence, particle size analysis, waterrequirement analysis, scanning electron microscopy, energy-dispersiveX-ray spectroscopy, surface area, specific gravity analysis,thermogravimetric analysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio. One or more of the preceding tests may be consider API tests, asset forth in the API recommended practice for testing well cements(published as ANSI/API recommended practice 10B-2). Additional API testsnot specifically listed above may also be used for the measurements. Thephysical and chemical properties may be measured for a group of cementcomponents. Two or more of the cement components measured may bedifferent types of cement components (e.g., volcanic rock, CKD, fly ash,etc.). Two or more of the cement components may be the same type butfrom different sources (e.g., volcanic rock from source 1, volcanic rockfrom source 2, etc.).

X-ray powder diffraction is one analysis technique that may be used formeasuring the physical and chemical properties of the cement components.X-ray powder diffraction is a technique of exposing a sample to x-rays,neutrons, or electrons and measuring the amount ofinter-atomic-diffraction. The sample acts a diffraction grating therebyproducing a differing signal at different angles. The typical propertiesthat may be measured are the phase identification for the identificationand characterization of a crystalline solid. Other properties may becrystallinity, lattice parameters, expansion tensors, bulk modulus, andphase transitions.

X-ray fluorescence is another analysis technique that may be used formeasuring the physical and chemical properties of the cement components.X-ray fluorescence may use short wave x-rays to ionize atoms in a samplethereby causing them to fluoresce at certain characteristic wavelengths.The characteristic radiation released by a sample may allow accurateidentification of the component atoms in the sample as well as theirrelative amounts.

Particle size analysis is another analysis technique that may be usedfor measuring the physical and chemical properties of the cementcomponents. Particle size analysis may be accomplished through analysisby various laboratory techniques including but not limited to laserdiffraction, dynamic light scattering, static image analysis, anddynamic image analysis. Particle size analysis may also provideinformation about the morphology of a particular sample. Morphology mayinclude parameters such as sphericity and roundness as well as thegeneral shape of a particle such as disk, spheroid, blade, or roller.With a knowledge of the morphology and particle size, the averagesurface area and volume may be estimated. Surface area and volume may beimportant in determining the water requirement as well as reactivity. Ingeneral, a relatively smaller particle size may react more quickly thana relatively larger particle size. Also the relatively smaller particlesize may have a greater water requirement to completely hydrate than arelatively larger particle size.

Energy dispersive x-ray spectroscopy is another analysis technique thatmay be used for measuring the physical and chemical properties of thecement components. Energy dispersive x-ray spectroscopy is an analyticaltechnique used to analyze the elements present in a sample and determinethe chemical characterization of a sample. Other techniques may includeFourier transform infrared spectroscopy, ultraviolet-visiblespectroscopy, mass spectroscopy, secondary ion mass spectrometry,electron energy mass spectrometry, dispersive x-ray spectroscopy, augerelectron spectroscopy, inductively coupled plasma mass spectrometry(ICP-MS), thermal ionization mass spectroscopy, glow discharge massspectroscopy, and x-ray photoelectron spectroscopy.

The cement components may be analyzed to determine their waterrequirement. Water requirement is typically defined as the amount ofmixing water that is required to be added to a powdered, solid materialto form a slurry of a specified consistency. Water requirement for aparticular cement component may be determined by a process that includesa) preparing a Waring blender with a specified amount of water, b)agitating the water at a specified blender rpm, c) adding the powderedsolid that is being investigated to the water until a specifiedconsistency is obtained, and d) calculating the water requirement basedon the ratio of water to solids required to reach the desiredconsistency.

The cement components may be analyzed to determine their specificsurface area. Specific surface area generally refers to the totalsurface area and may be reported as the total surface area per unitmass. Values obtained for specific area are dependent on the analysistechnique. Any suitable analysis technique may be used, including,without limitation adsorption, adsorption based methods such asBrunauer-Emmett-Teller (BET) analysis, methylene blue staining, ethyleneglycol monoethyl ether adsorption, and a protein-retention method, amongother.

Thermogravimetric analysis is another analysis technique that may beused for measuring the physical and chemical properties of the cementcomponents. Thermogravimetric analysis is a method of thermal analysiswherein changes in physical and chemical properties of a sample may bemeasured. In general the properties may be measured as a function ofincreasing temperature, such as with a constant heating rate, or as afunction of time with a constant temperature or a constant mass change.Properties determined by thermogravimetric analysis may includefirst-order phase transitions and second-order phase transitions such asvaporization, sublimation, adsorption, desorption, absorption,chemisorption, desolvation, dehydration, decomposition, oxidation andreduction reactions, ferromagnetic transition, superconductingtransition, and others.

In addition to determining physical and chemical properties of thecement components themselves, laboratory tests may also be run todetermine behavior of the cement components in a cement composition. Forexample, the cement components may be analyzed in a cement compositionto determine their compressive strength development and mechanicalproperties. For example, a preselected amount of the cement componentmay be combined with water and lime (if needed for setting). Themechanical properties of the cement composition may then be determinedincluding, compressive strength, tensile strength, and Young's modulus.Any of a variety of different conditions may be used for the testing solong as the conditions are consistent for the different cementcomponents.

Compressive strength is generally the capacity of a material orstructure to withstand axially directed pushing forces. The compressivestrength of the cement component may be measured at a specified timeafter the cement component has been mixed with water and the resultantcement composition is maintained under specified temperature andpressure conditions. For example, compressive strength can be measuredat a time in the range of about 24 to about 48 hours (or longer) afterthe fluid is mixed and the fluid is maintained at a temperature of from100° F. (37.77° C.) to about 200° F. (93.33° C.) and atmosphericpressure. Compressive strength can be measured by either a destructivemethod or non-destructive method. The destructive method physicallytests the strength of treatment fluid samples at various points in timeby crushing the samples in a compression-testing machine. Thecompressive strength is calculated from the failure load divided by thecross-sectional area resisting the load and is reported in units ofpound-force per square inch (psi). Non-destructive methods typically mayemploy an Ultrasonic Cement Analyzer (“UCA”), available from Fann®Instrument Company, Houston, Tex. Compressive strengths may bedetermined in accordance with API RP 10B-2, Recommended Practice forTesting Well Cements, First Edition, July 2005.

Tensile strength is generally the capacity of a material to withstandloads tending to elongate, as opposed to compressive strength. Thetensile strength of the cement component may be measured at a specifiedtime after the cement component has been mixed with water and theresultant cement composition is maintained under specified temperatureand pressure conditions. For example, tensile strength can be measuredat a time in the range of about 24 to about 48 hours (or longer) afterthe fluid is mixed and the fluid is maintained at a temperature of from100° F. (37.77° C.) to about 200° F. (93.33° C.) and atmosphericpressure. Tensile strength may be measured using any suitable method,including, without limitation, in accordance with the proceduredescribed in ASTM C307. That is, specimens may be prepared in briquettemolds having the appearance of dog biscuits with a one square inchcross-sectional area at the middle. Tension may then be applied at theenlarged ends of the specimens until the specimens break at the centerarea. The tension in pounds per square inch at which the specimen breaksis the tensile strength of the material tested.

Young's modulus also referred to as the modulus of elasticity is ameasure of the relationship of an applied stress to the resultantstrain. In general, a highly deformable (plastic) material will exhibita lower modulus when the confined stress is increased. Thus, the Young'smodulus is an elastic constant that demonstrates the ability of thetested material to withstand applied loads. A number of differentlaboratory techniques may be used to measure the Young's modulus of atreatment fluid comprising a cementitious component after the treatmentfluid has been allowed to set for a period of time at specifiedtemperature and pressure conditions.

Although only some select laboratory techniques may have been mentioned,it should be understood that there may be many analytical techniquesthat may be appropriate or not appropriate for a certain sample. One ofordinary skill in the art with the benefit of this disclosure should beable to select an appropriate analytical technique to determine acertain property of interest.

Once the analytical techniques have been performed on the cementcomponents, the data may be categorized and correlated. Some categoriesmay include, but are not limited to, specific surface area, morphology,specific gravity, water requirement, etc. In some examples, thecomponents may be categorized by relative amounts, including amount ofat least one of the following: silica, alumina, iron, iron, calcium,calcium, sodium, potassium, magnesium, sulfur, oxides thereof, andcombinations thereof. For example, the components may be categorizedbased on an oxide analysis that includes without limitation, silicacontent, calcium oxide content, and alumina content among other oxidesthat may be present in the cement component. In addition, correlationsbetween the cement components may be generated based on the data orcategorization of the data. Additionally, correlations may be defined orgenerated between properties of the cement components based on the data.For example, the various categories of properties may be plotted againstone another. In some examples, water requirement versus specific surfacearea may be plotted. Accordingly, the water requirement of the cementcomponent may be correlated to the specific surface area so that thespecific surface area is a function of water requirement. Specificsurface area may be used to predict reactivity of a cement component (orcomponents). However, specific surface area may not always be availablefor each material as specific surface area analysis typically requires aspecialized instrument. Accordingly, if the water requirement may beobtained for the cement component, the correlation between waterrequirement and specific surface area may be used to obtain an estimatefor specific surface area, which may then be used to predict reactivity.In addition to correlations between specific surface area andreactivity, correlations may also be made between specific surface areaand other mechanical properties such as tensile strength and Young'smodulus.

Some cement components that are alkali soluble may comprise reclaimed ornatural materials. Specifically silica containing cement components maycomprise materials such as mined materials, for example volcanic rock,perlite, waste materials, such as fly ash and CKD, and agriculturalashes as previously described. In some examples the cement componentthat is alkali soluble may have synergistic effects with a Portlandcement while others may be incompatible. In some examples a cementcomponent that is alkali soluble may cause gelation, high heatgeneration, water retention, among other effects. These and othereffects may be realized during laboratory testing of the cementcomponent in a cement composition comprising Portland cement. Laboratoryequipment may be configured to detect the effects of the cementcomponent on the composition. In some examples, equipment such acalorimeter may measure and quantify the amount of heat generation perunit mass of the cement component. Viscometers may measure the increasein gelation caused by the cement component. Each of the physical effectscaused by the addition of the cement component may be measured atseveral concentrations and then categorized, e.g., plotted or mapped.Once a component is mapped, the effect of adding the component to acement composition may be predicted by referencing the categorization.

As mentioned previously, some cement components that are alkali solublemay induce gelling when included in a cement composition. Although ahigher gelling rate may be undesirable in some examples, in otherexamples, a higher gelling rate may be advantageous or necessary to meetthe engineering design criteria. Usually one of ordinary skill in theart would select a suitable gelling agent or viscosifier for use in thecement composition. With the benefit of mapping, one of ordinary skillshould be able to select a cement component that is alkali soluble thatmay serve a dual purpose. For example, a cement component may increasethe compressive strength of a cement composition but also increase thegelling during mixing. If the engineering design criteria require ahigher gelling during mixing, it may be advantageous to include thecement component that increases the compressive strength while alsoincreasing gelling. The inclusion of a cement component that exhibitsmultiple effects may reduce the amount of additional additives, such asgelling agents or viscosifiers, needed, which may be high cost. Sincethe component's gelling effect may have been documented in a map, theamount of component to include in a cement composition may be readilydetermined.

Another potentially advantageous physical effect that may becharacterized is dispersing ability. Some cement components may compriserelatively spherical particles. The relatively spherical particles mayexert a “roller bearing” effect in a cement composition with water. Theeffect may cause the other components in the cement composition tobecome more mobile thereby dispersing the components in the cementcomposition. If particles that are roughly 1/7^(th) or smaller than theprimary component in a slurry, then the apparent viscosity may decrease.Another potentially advantageous physical property that may be mapped issurface area. Surface area may relate to density wherein a relativelyhigher surface area particle may lower the density of a cementcomposition. Particles which lower the density may be used as a lowdensity additive. Another potentially advantageous effect that may bemapped is particle size. Components with relatively smaller particlesizes may have the ability to form a filter cake against a formationthereby blocking cement slurry from escaping into a formation. Cementcomponents with a small particle size may be used as a fluid losscontrol agent. With the benefit of the present disclosure, one ofordinary skill should be able to select a cement component and map itsproperties. One of ordinary skill should also be able to select asecondary property of interest of the cement component and with thebenefit of the map, create a slurry with the desired properties.

Another potential benefit of replacing traditional cement additives withsilica based cement components is a reduction in cost. A silica basedcement component may partially or fully replace a relatively moreexpensive cement additive as discussed above. The cost of the cementcomposition may be improved by balancing the required engineeringparameters such as compressive strength, mixability, free water content,and others in order to maximize the amount of relatively lower costsilica based cement components. Any remaining deviation from theengineering requirement may be “made up” with the relatively moreexpensive cement additive. In this way, the cement composition may bereduced to a minimum cost per pound since the engineering requirementsare met with a blend of primarily lower cost components.

Once the data is collected by the chosen laboratory techniques,categorized, and mapped, several operations may be performed on the datain order to yield predictions about a cement composition that comprisesmapped cement components. Set properties, for example, may be estimated.A method of estimating the material reactivity based on the reactiveindex will be described below. Material reactivity may be based on manyparameters such as specific surface area and specific gravity, amongothers. Another use for the mapped data may be to increase cement slurryperformance based on parameters such as particle shape, particle size,and particle reactivity. The data may also be used to predict andcapture slurry density dependence of compressive strength and use theinsight gathered to design improved cement formulations. The data mayalso be used to predict a slurry composition to achieve an improvedcement formulation. The criteria for just right may be compressivestrength, cost, rheology, mechanical properties, fluid loss controlproperties, thickening times, and others.

Reactivity mapping may be used to estimate various mechanical propertiesof a cement component, including compressive strength, tensile strength,and Young's modulus. As previously described, correlations may be madebetween specific surface area and certain mechanical properties, such asreactivity, tensile strength, and Young's modulus. Using thesecorrelations the mechanical properties for a cement component orcombination of cement components may be predicted.

One technique that may be used to correlate reactivity and specificsurface area is the reactive index. Without being limited by theory, thereactive index of a cement component may be referred to as a measure ofthe cement component's reactivity as adjusted for differences in surfacearea. It is important to note that the term “cement component” refers toany material that is cementitious when mixed with water and/or lime anda suspending agent, when necessary, such that the slurry is stable. A“cementitious reactive index” CRI_(i) can be defined as, but not limitedto, Equation 1 as follows:CRI_(i)=ƒ_(CRI)(CS_(i),ρ_(i),SSA_(PSDi),)  [1]

-   -   Where:    -   CS_(i)=Unconfined UCS (ultimate compressive strength) obtained        from samples cured at specific reference temperature, pressure        and age.    -   ρ_(i)=Density of slurry that was prepared and cured for        measuring UCS SSA_(PSDi)=Specific surface area obtained by        typical particle size analysis methods.        A “physicochemical index” (PCI) of the cementitious component        may be defined as, but not limited to Equation 2:        PCI_(i)=ƒ_(PCI)(SA_(i),SG_(i) ,D ₅₀ ,C _(Si) ,C _(Ca) ,C _(Al)        ,C _(Na) ,C _(Fe) ,C _(other species))  [2]    -   Where:    -   SA_(i)=Surface area of the cementitious component i,    -   SG_(i)=specific gravity of the cementitious component i,    -   D₅₀=mass average or volume average diameter of the particle size        distribution of cementitious component i,    -   C_(Si)=Mass concentration of silica oxide of component i,    -   C_(Ca)=Mass concentration of calcium oxide of component i,    -   C_(Al)=Mass concentration of Aluminum oxide of component i,    -   C_(Na)=Mass concentration of sodium oxide of component i,    -   C_(Fe)=Mass concentration of iron oxide of component i,

It should be noted that the mass concentrations referenced above andhere to for, may be measured, but is not limited to X-ray fluorescencespectroscopy measuring technique and a reference to “component i” isequivalent to “cementitious component i”. The functions in Equations 1and 2 that define CRI_(i) and PCI_(i), when properly defined, thefollowing universal relationship may hold for a wide range ofcementitious materials such as, but not limited to, Portland cements;fly ash; other pozzolanic materials; other ashes; etc.CRI_(i)=ƒ_(CRI-PCI)(PCI_(i))  [3]FIG. 1 is a graph of Equation 1 versus Equation 2, for real data,illustrating the accuracy of Equations 1, 2 and 3 when applied to fivedifferent types of cementitious material sources and three samples ofsimilar materials but from different sources. The simulated data wasfound to have a relationship of y=36.252x^(0.2256,) wherein R²=0.9406.

In some examples, the form of Equation 3 may be a power law, such as inEquation 4.CRI_(i) =A{PCI_(i)}^(B)  [4]A and B are coefficients that may be unique the various species andsources of cementitious materials selected. Once the generalizedfunction defined in Equation 4 is defined for a given population orgroup of cementitious components, a linear or nonlinear summationrelationship further defined below, may be used in conjunction withEquation 5 to predict the UCS of various combinations of cementitiousmaterials for specified slurry densities, temperatures, pressures andcuring age.CRI_(c) =A{PCI_(c)}^(B)  [5]

-   -   Where,    -   CRI_(c) is defined as the CRI for the unique combination of n        cementitious components as the composite, and similarly    -   PCI_(c) is defined as the Physicochemical Index for the        composite.        A given composite with mass of m_(c) is defined as:        m _(c)=ƒ_(i)+ƒ_(i+1)+ƒ_(i+2)+ . . . +ƒ_(n)  [6]        Where: ƒ_(i) is defined as the mass fraction of the cementitious        component i, and n is the total number of independent        cementitious components. Once the function is defined in        Equation 5, then the composite value of the physicochemical        reactive index may be computed using Equation 7 as follows:        PCI_(c)=ƒ₁PCI₁+ƒ₂PCI₂+ƒ₃PCI₃+ . . . +ƒ_(n)PCI_(n)  [7]

Where: PCI_(c) is defined as the overall chemical reactive index for ablend of n number of uniquely independent cementitious components, ƒ_(i)is defined as the mass fraction of the cementitious component i, and nis the total number of independent cementitious components. Once PCI_(c)has been determined for specific assumed blend of selected cementitiouscomponents, then the linear or non-linear summations (Equations 8 and 9)are determined for the following terms:ρ_(c)=ƒ₁ρ₁+ƒ₂ρ₂+ƒ₃ρ₃+ . . . +ƒ_(n)ρ_(n)  [8]and,SSA_(PSDc)=ƒ₁SSA_(PSD1)+ƒ₂SSA_(PSD2)+ƒ₃SSA_(PSD3)+ . . .+ƒ_(n)SSA_(PSDn)  [9]PCI_(c) is used to compute the value of CRI_(c) using either Equation 5or the more generalized form of Equation 3 for the composite terms. OnceCRI_(c) is determined for the given composite blend, then the compositevalues of ρ_(c) and SSA_(PSDc) may be used along with Equation 10 topredict the actual compressive strength of the composite blend, CS_(c).CRI_(c)=ƒ_(CRI)(CS_(c),ρ_(c),SSA_(PSDc),density of slurry)  [10]Experimental data was collected for specific composite blends and issummarized in the table below:

TABLE 1 Mass Fractions of Cementitious Components Cementitious CompositeComposite Composite Component Blend 1 Blend 2 Blend 3 A 0.36 0.53 B 0.32C 0.32 0.31 D 0.33 E 0.32 F 0.35 G 0.16 Totals 1.00 1.00 1.00It is important to note that each of the cementitious components abovewere either distinctly different species (type) of cementitiouscomposition and/or from a different source.

FIG. 2 is another plot of Equation 1 versus Equation 2 for real data,showing the accuracy of Equations 1, 2, and 3. Equations 1 through 10may also be used for predicting other mechanical properties, includingbut not limited to, Young's Modulus of Elasticity and Tensile Strength.Additionally, it should be noted that even though a “linear summation”technique is presented in the previous development, that this inventionalso includes other methods such as the non-linear summation methodpresented in Equation 11.PCI_(c)=(1+ƒ₁)^(a1)PCI₁+(1+ƒ₂)^(a2)PCI₂+(1+ƒ₃)^(a3)PCI₃+ . . .+(1+ƒ_(n))^(an)PCI_(n)  [11]Where: ai are exponents that are determined for a unique set ofcementitious components.

Further examples using the chemical reactive index, water requirementand other analytical parameters will now be discussed. A statisticaltable may be generated that plots chemical reactive index against waterrequirement. An example is shown in Table 2.

TABLE 2 Chemical Reactive Index Vs. Water Requirement Water High X1 X4,X5 X8 Requirement Medium X2 X6 X9, X10 Low X3 X7 X11 . . . Xn Low MediumHigh Reactive Index

Other analytical parameters such as particle size versus chemicalreactive index, heat generation versus chemical reactive index, andothers may also be used. By ranking the chemical reactive index againstan analytical parameter, a blend of components may be selected that hasa minimized cost and an improved chemical reactive index while stillhaving a mixable composition. In some examples, a selected cementcomposition may have too much free water to set properly. In suchexamples, a component having a high water requirement may be selected toreplace a component in the cement composition or supplement the cementcomposition. The selected component having the high water requirementmay be selected based on the chemical reactive index to ensure that theoverall blend has sufficient reactivity. A cement composition comprisingthe selected cement component may exhibit less free water due to thehigh water requirement of the component and may also exhibit the samereactivity from selecting the appropriate chemical reactive index. Thereactivity of a cement composition may be tuned based on the selectionof cement component having the desired reactivity. A component having ahigh reactivity may exhibit a faster set time than one with a lowreactivity.

The reactivity of a cement composition may be affected by wellboretemperature. If a wellbore has a relatively low temperature, about <150°F. or less, a component having a relatively higher reactivity may berequired to ensure that the cement composition develops adequatestrength. In previous cement compositions, a chemical accelerator mayhave been used to enhance the reaction speed in a relatively lowertemperature well. A cement composition comprising a relatively higherchemical reactive index component may not require an accelerator due tothe high reactivity of the component. Cement compositions comprising ahigh reactivity component may not require an accelerator and thereforemay have a lower overall cost. If a wellbore has a relatively hightemperature, about >150° F. or greater, the cement component may beselected to have a relatively lower reactivity. Selecting a lowerreactivity may be advantageous when the high temperature of a wellboremay cause the cement composition to set too quickly. In previous cementcompositions, a cement set retarder may have been used to reduce thereaction speed in a relatively higher temperature well. By selecting arelatively lower reactivity component, the cement set reaction maypotentially be slowed without the use of a retarder. Selecting anappropriate cement component based on reactivity may reduce the cost ofthe cement composition by eliminating or reducing the need foraccelerators and retarders. Furthermore, a combination of cementcomponents may be blended to control the reactivity, for example byadding low, medium, and high reactivity cement components, a cementcomposition may be created that has a controlled reactivity along thespectrum of wellbore temperatures. One of ordinary skill in the art,with the benefit of this disclosure, should recognize the appropriateamount and type of cement component to include for a chosen application.

Another application of the previously mention statistical correlationmay be in classifying cement components by cost among other factors. Ingeneral, the reactivity of a cement composition may be maximized toensure that the cement composition will attain enough compressivestrength to meet the design requirement of a particular well. If aspecific cement composition far exceeds the engineering requirements,then an alternate cement composition comprising potentially lessexpensive components may be formulated. The following equationsillustrate an improvement scheme for a cement composition.

$\begin{matrix}{{CRI},{{composite} = {\sum( {{CRI}_{i}*\%{Concentration}} )}}} & \lbrack 12\rbrack\end{matrix}$ $\begin{matrix}{{{Cost}{Index}},{{composite} = {\sum( {{Cost}_{i}*\%{Concentration}} )}}} & \lbrack 13\rbrack\end{matrix}$ $\begin{matrix}{ {{Optimized}{Blend}}arrow{\max{CRI}} ,{{composite}\Lambda\min{Cost}{Index}},{composite}} & \lbrack 14\rbrack\end{matrix}$ $\begin{matrix}{{{Optimization}{Ratio}} = {\max\lbrack \frac{{CRi},{composite}}{{{Cost}{Index}},{composite}} \rbrack}} & \lbrack 15\rbrack\end{matrix}$ $\begin{matrix}{{{{Constraints}:{Cost}{Index}} < {\$ C}},{{{where}C} \geq 0}} & \end{matrix}$ $\begin{matrix}{{{CS} =  {f( {{CRI},{{analytical}{properies}}} )}arrow{CS} },} & \end{matrix}$ min  < CS, composite < CS, max 

Using all the techniques previously discussed, a cement compositionhaving a minimized cost and a maximized reactivity may be calculated. Afirst step may be to identify the engineering requirements of aparticular well. Another step may be to define the inventory availableat a particular field camp or well site. As previously mentioned, aparticular region may have access to only a certain amount or kind ofcement components. Some of the factors that may be considered inaddition to those previously mentioned are the cost of goods sold, bulkdensity, and specific gravity for the available and potential inventory.The available cement components may be tested in a laboratory andclassified using the methods previously discussed. Analytical study maycomprise the various analytical techniques previously mentioned alongwith the physiochemical reactivity measurements for compressivestrength, young's modulus, water requirement, and others. Next thecorrelations between the mechanical performance measures and analyticalproperties may be calculated. The chemical reactive index may also becalculated. A statistical table of the chemical reactive index and thewater requirement may be calculated along with the chemical reactiveindex versus other selected analytical parameters.

An initial virtual design may be selected and tested to see if it meetsthe functional requirements defined by the engineering parameters. Theinitial virtual design may be based on a previous design, chosen fromfield experience, or selected by a computer. The virtual design may bebased on, among other factors, the chemical reactivity of the cementcomponents. If the virtual design meets all of the engineeringparameters, a cost index for the composition may be calculated. Thecomponents of the cement composition may be adjusted iteratively until acement composition having the maximum reactive index and minimized costis achieved. In some examples, a fluid loss control additive, thickeningadditive, or other cement additives may be necessary to meet thefunctional requirements. As was previously described, the amount ofcement additives that may need to be added to a cement composition maybe minimized by selecting cement components that have inherentproperties such as high reactive index, low water requirement, fluidloss control properties, and dispersive properties, among others.

A relationship between Young's modulus and compressive strength may beexpressed as in Equation 16.Y=A _(ym)*ƒ(ρ)*g(CS)  [16]Where ƒ and g are functions that use density and compressive strength asinputs. A more specific form of this relationship may be expressed inEquation 17 as follows:YM=A _(ym)(ρ)^(Bden)(CS)^(Bcs)  [17]

Where:

A_(YM), Bden, Bcs are constants for a given family of cementitiousformulations

ρ=density

CS=compressive strength

YM=Young's modulus

Equation 16 can also be written to determine the compressive strength.

$\begin{matrix}{{CS} = \{ {\lbrack \frac{Y{M( {psi} )}}{A_{ym}} \rbrack\lbrack \frac{1}{\rho^{Bden}} \rbrack} \}^{1/{Bcs}}} & \lbrack 18\rbrack\end{matrix}$

Each of density, compressive strength, and Young's modulus may have anyunits appropriate for a particular application. For example, the unitsof density may be units of lbm/gal, kg/m³, or any other appropriateunits. Compressive strength may have units of psi, pascal, or any otherappropriate units. Young's modulus may have units of psi, pascal, or anyother appropriate units.

The constants of Equations 16 and 17 may be determined for a particularblend or system of cementitious components. A cement system may bedefined as the base ingredients that are required to form a cementitiousmixture that can set to form a hardened mass when combined with water.Each system may have a particular set of constants for Equation 16. Forexample, a cement composition comprising class H Portland cement, classC fly ash, and pumice may have differing constants than a cementcomposition comprising pumice, hydrated lime, metakaolin, and class Cfly ash. As previously discussed, Young's modulus may be modulated bychanging a concentration of one or more of the cementitious components.Constants of Equation 16 may be determined by preparing a plurality ofcement composition with varying concentrations of each ingredient andtesting the Young's modulus of each resulting set composition. Young'smodulus may be plotted and a regression analysis may be performed tofind the constants of Equations 16 and 17. For Equation 17, at leastthree cement compositions must be prepared as there are three degrees offreedom to determine the three constants in Equation 17.

A cement for use in a wellbore may have a particular Young's modulus anddensity requirement provided by a customer, regulations, determined bybest practices, determined by previously completed cement jobs, or anyother means. A particular cement system may be chosen for a variety ofreasons including, but not limited to, formation compatibility andcompressive strength requirement. Constants for Equation 17 may be knownfor the selected cement system and in conjunction with density andYoung's modulus requirements, Equation 18 may be used to determine aninitial compressive strength value. The previously discussed designprocess for a slurry using reactive index or any other method may beapplied to generate a first cement composition. The first compositionmay be tested for a first compressive strength and first Young'smodulus. A second and third composition may be generated wherein thesecond and third compositions have compressive strengths greater andless than the first compressive strength.

Each of the first, second, and third compressive strengths and Young'smodulus may be plotted and Equation 18 may be fit to the plotted datausing regression analysis to determine new quantitative values forconstants Aym, Bden, and Bcs. The quantitative values for the constantsmay allow for greater precision in calculating the required Young'smodulus for a particular compressive strength target.

Once quantitative values for the constants is known, Equation 18 may beused with the Young's modulus and density requirement to compute arevised compressive strength that may result from the Young's modulusinput. The previously discussed slurry design process may be used withthe new computed compressive strength to design a cement compositionthat meets the compressive strength requirements. The designed slurrymay then be tested for compressive strength and Young's modulus toconfirm the composition meets or exceeds the design requirements.

Although described herein in terms of Equations 16-18, one of ordinaryskill in the art will appreciate that there may be other functions thatmay be used to correlate Young's modulus and compressive strength.

Rearranging Equation 10 results in Equation 19, that can be used tocompute a correlation between the mass ratio of water to cementitiousmaterial (w/c) in a cement slurry (Abram's law).CS_(c)=ƒ_(CSc)(CRI_(c),ρ_(c),SSA_(PSDc),density of slurry)  [19]

Equation 18 and Equation 16 may be combined to form Equation 20 whereYoung's modulus is expressed in terms of density for a given cement dryblend.YM=A _(ym)(ρ)^(Bden)(CS_(c))^(Bcs)  [20]

An alternate method of modeling Young's modulus may be from acorrelation with slurry composition, curing temperature, and density.Equation 21 illustrates an example of a model where (cement blendcomposition) may be a complex function with dependence onphysio-chemical properties of the constituent species in thecomposition, g(T) may be, but not necessarily limited, to an Arrheniusfunction, and r(Density) may be but not limited to a power-law or anexponential. A complex function may include properties such as particlesize, surface area, water requirement, silica, calcium oxide, alumina,iron oxide, C2S, C3S, C3AF, and silicate content.YM=ƒ[(cement blend composition)*g(T)*r(Density)]  [21]

It will be appreciated by those of ordinary skill in the art, the cementcompositions disclosed herein may be used in a variety of subterraneanapplications, including primary and remedial cementing. The cementcompositions may be introduced into a subterranean formation and allowedto set. As used herein, introducing the cement composition into asubterranean formation includes introduction into any portion of thesubterranean formation, into near wellbore region surrounding thewellbore, or into both. In primary cementing applications, for example,the cement compositions may be introduced into the annular space betweena conduit located in a wellbore and the walls of the wellbore (and/or alarger conduit in the wellbore), wherein the wellbore penetrates thesubterranean formation. The cement composition may be allowed to set inthe annular space to form an annular sheath of hardened cement. Thecement composition may form a barrier that prevents the migration offluids in the wellbore. The cement composition may also, for example,support the conduit in the wellbore. In remedial cementing applications,the cement compositions may be used, for example, in squeeze cementingoperations or in the placement of cement plugs. By way of example, thecement compositions may be placed in a wellbore to plug an opening(e.g., a void or crack) in the formation, in a gravel pack, in theconduit, in the cement sheath, and/or between the cement sheath and theconduit (e.g., a microannulus).

While the present description refers to cement compositions and cementcomponents, it should be understood that the techniques disclosed hereinmay be used with any suitable wellbore treatment composition andcorresponding solid particulates of which cement compositions and cementcomponents are one example. Additional examples of slurry compositionsmay include spacer fluids, drilling fluids, cleanup pills, lostcirculation pills, and fracturing fluids, among others. Suitable solidparticulates may include any of a variety of inorganic particlescommonly used in well treatments

Accordingly, this disclosure describes systems, compositions, andmethods relating to slurry design process. Without limitation, thesystems, compositions and methods may further be characterized by one ormore of the following statements:

Statement 1. A method of generating a wellbore treatment fluidcomprising: obtaining a target Young's modulus; calculating acompressive strength requirement from a correlation comprisingcompressive strength and Young's modulus using the target Young'smodulus as an input; classifying a plurality of solid particulates usingcorrelations; calculating a reactive index and/or a water requirementfor at least one of the solid particulates; and selecting two or moresolid particulates from the plurality of solid particulates to create awellbore treatment fluid, wherein two or more solid particulates areselected such that when the wellbore treatment fluid is prepared andset, the set wellbore treatment fluid has a 24 hour compressive strengthgreater than or equal to the compressive strength requirement.

Statement 2. The method of statement 1 wherein the correlation isYM=A_(ym)*ƒ(ρ)*g(CS) where YM is Young's modulus, ƒ(ρ) is a functionwith density as an input, and g(CS) is a function with compressivestrength as an input.

Statement 3. The method of any preceding statement further comprisingadjusting one or more concentrations of the selected two or more solidparticulates to meet one or more desired parameters.

Statement 4. The method of any preceding statement wherein the one ormore desired parameters comprise a cost objective.

Statement 5. The method of any preceding statement wherein the one ormore desired parameters comprise at least one parameter selected fromthe group consisting of compressive strength, fluid loss, mud densities,slurry density, pore pressures, thickening time, tensile strength,Young's Modulus, Poisson's Ratio, rheological properties, slurrystability, fracture gradient, remaining well capacity, transition time,free fluid, gel strength, and combinations thereof.

Statement 6. The method of any preceding statement further comprisinganalyzing the solid particulates to generate data about physical andchemical properties of the solid particulates and generatingcorrelations between the solid particulates based on the data.

Statement 7. The method of any preceding statement wherein the analyzingthe solid particulates comprises analysis by one or more techniquesselected from the group consisting of microscopy, spectroscopy, x-raydiffraction, x-ray fluorescence, particle size analysis, waterrequirement analysis, scanning electron microscopy, energy-dispersiveX-ray spectroscopy, surface area, specific gravity analysis,thermogravimetric analysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio, API testing, and combinations thereof.

Statement 8. The method of any preceding statement further comprisinggenerating a statistical table comprising two or more differentparameters of the solid particulates.

Statement 9. The method of any preceding statement, wherein thedifferent parameters comprise the water requirement and the reactiveindex.

Statement 10. The method of any preceding statement, further comprisingintroducing the wellbore treatment fluid into a well bore.

Statement 11. The method of any preceding statement, wherein thewellbore treatment fluid is introduced into the wellbore using one ormore pumps.

Statement 12. The method of any preceding statement, further comprisingmixing the components of the wellbore treatment fluid using mixingequipment, the components comprising the two or more solid particulates.

Statement 13. A method of improving a wellbore treatment fluid, themethod comprising: calculating a compressive strength requirement usinga target Young's modulus as an input in a correlation comprisingcompressive strength, Young's modulus, and at least one constant;selecting a target reactive index for the wellbore treatment fluid basedon the compressive strength requirement; generating a wellbore treatmentfluid based on the target reactive index; adjusting the at least oneconstant from the correlation based on a compressive strengthmeasurement, Young's modulus measurement, or both of the wellboretreatment fluid to generate an updated at least one constant;calculating a second compressive strength requirement using the targetYoung's modulus as an input in a correlation comprising compressivestrength, Young's modulus, and updated at least one constant; selectinga second target reactive index for the wellbore treatment fluid based onthe second compressive strength requirement; generating a secondwellbore treatment fluid based on the second target reactive index.

Statement 14. The method of statement 13 wherein the correlation isYM=A_(ym)*ƒ(ρ)*g(CS) where YM is Young's modulus, ƒ(ρ) is a functionwith density as an input, and g(CS) is a function with compressivestrength as an input.

Statement 15. The method of statements 13-14 wherein the reactive indexis calculated at a bottom hole circulating temperature.

Statement 16. The method of statements 13-15 wherein the second wellboretreatment fluid further comprises at least one additive selected fromthe group consisting of weighting agents, retarders, accelerators,activators, gas control additives, lightweight additives, gas-generatingadditives, mechanical-property-enhancing additives, lost-circulationmaterials, filtration-control additives, fluid-loss-control additives,defoaming agents, foaming agents, transition time modifiers,dispersants, thixotropic additives, suspending agents, and combinationsthereof.

Statement 17. The method of statements 13-16 further comprisingcalculating a cost of the wellbore treatment fluid.

Statement 18. A system for generating a wellbore treatment fluidcomprising: a model correlation comprising compressive strength, Young'smodulus, and at least one constant; a plurality of solid particulates;and a computer system operable to accept a target Young's modulus inputfrom a user and generate a wellbore treatment fluid using the targetYoung's modulus input to the model correlation, wherein the wellboretreatment fluid comprises at least two solid particulates selected formthe plurality of solid particulates and wherein a concentration of eachof the at least two solid particulates is based on a target property.

Statement 19. The system of statement 18 wherein the correlation isYM=A_(ym)*ƒ(ρ)*g(CS) where YM is Young's modulus, ƒ(ρ) is a functionwith density as an input, and g(CS) is a function with compressivestrength as an input.

Statement 20. The system of statements 18-19 wherein the computer systemis further operable to improve the wellbore treatment fluid bycalculating a reactive index and adjusting a relative amount of each ofthe solid particulates to meet or exceed the target property.

Statement 21. The system of statements 18-20 further comprising adatabase, wherein the database comprises the solid particulates, a costcorresponding to each of the solid particulates, a water requirement foreach component, and a reactive index for each component.

Statement 22. The system of statements 18-21 wherein the target reactiveindex is defined by a user or automatically selected by the computersystem.

Statement 23. The system of statement 18-22 wherein the computer systemis configured to select an additive to include in the wellbore treatmentfluid, wherein the additive comprises at least one additive selectedfrom the group consisting of weighting agents, retarders, accelerators,activators, gas control additives, lightweight additives, gas-generatingadditives, mechanical-property-enhancing additives, lost-circulationmaterials, filtration-control additives, fluid-loss-control additives,defoaming agents, foaming agents, transition time modifiers,dispersants, thixotropic additives, suspending agents, and combinationsthereof.

Statement 24. The system of statements 18-23 wherein the computer systemis further operable to select the solid particulates based on a waterrequirement.

Examples of the methods of using the preceding techniques will now bedescribed in more detail with reference to FIG. 3 . A system 300 foranalyzing the cement component is illustrated. The system 300 maycomprise a cement component sample 305, analytical instrument 310, andcomputer system 315. Cement component sample 305 may be any cementcomponent of interest. Cement components as previously described may begenerally categorized as alkali soluble. The cement component sample maybe placed or fed into analytical instrument 310. In some examples,analytical instrument 310 may be configured to automatically feed cementcomponent sample 305 into analytical instrument 310. Analyticalinstrument 310 may be configured to analyze the physical and chemicalproperties of cement component sample 305. As previously described,physical and chemical properties may comprise, without limitation,morphology, chemical composition, water requirement, and others. Thedata generated by analytical instrument 310 may be sent to computersystem 315 for processing. Computer system 315 may comprise a processor,memory, internal storage, input and output means, network connectivitymeans, and/or other components common to computer systems. Computersystem 315 may take the data from analytical instrument 310 as input andstore it in the storage for later processing. Processing the data maycomprise inputting the data into algorithms which compute a result.Processing the data may also comprise organizing the data and mappingthe data as previously described. In particular, the computer system maycomprise algorithms configured to process the data to generate apredictive model of the physical and chemical behavior of cementcomponent sample 305. Predictive models may be stored in a predictivemodel database 320 which may be stored locally or on a network. Thepredictive model database 320 may comprise all previous predictivemodels generated by the algorithms as well as maps of the generated dataas well as the raw data.

Referring now to FIG. 4 , a system 400 for generating cementcompositions is illustrated. The system 400 may comprise a predictivemodel database 320 and computer system 410. In some examples, computersystem 410 may be the same computer system 315 of FIG. 3 . A user input420 may define engineering parameters such as the required compressivestrength of a cement slurry, the bottom hole static temperature of thewellbore, mud densities, pore pressures, total vertical depth, measureddepth, the required rheological properties of the slurry, the thickeningtime of the slurry, cement materials, cement additives, free fluid,permeability, pore pressure, fracture gradient, mud weight, density, gelstrength, stability, suspension, remaining well capacity, transitiontime, acid resistance, salt tolerance, and other parameters. Computersystem 410 may be configured to input user input 420 and the predictivemodels, maps, and data stored in predictive model database 320 into apredictive cement algorithm. The predictive cement algorithm maygenerate a cement composition or compositions that meet the engineeringrequirements define by the user input 420. The output 430 of thepredictive cement algorithm may contain the relative amounts of eachcement component in the generated cement composition as well as thepredicted material properties of the cement composition.

For example, if a user selects Portland cement, fly ash, and volcanicrock as the cement materials available the computer system may querypredictive model database 320 for the required models, maps, and datacorresponding to the cement materials. As previously described, theremay be many different parameters such as particle size, regional sourceof the cement material, among others that may determine which set ofdata that is retrieved from predictive model database 320. Thepredictive cement algorithm may be configured to improve the outputcement slurry based on one or more parameters such as cost, compressivestrength, or any other chosen parameter. In some examples the predictivecement algorithm may optimize on two or more variable. Optimize in thiscontext should not be understood as arriving at a best result but ratherthat the cement algorithm is configured to iterate on one or morevariables. The output of the algorithm in this example may be forexample, 30% Portland by weight, 30% volcanic rock by weight, 20% flyash, and 20% lime, with a 120% excess by weight of water. The generatedslurry may conform within a margin of error to the engineeringparameters supplied by user input 420. The generated slurry may be addedto predictive model database 320 to be used in future calculations.

As previously discussed, the cement components may have secondaryeffects such as gelling, dispersive properties, heat generation, andother secondary effects previously mentioned in addition to the primaryeffect of being cementitious when included in a cement composition. Thesecondary effects may be beneficial as well. For example, if a cementcomposition requires a thickening agent, instead of using a separateadditive to thicken the cement composition, a cement component that gelsmay be used in the place of another additive. Other secondary effectsmay also be taken advantage of in a similar manner. The predictivecement algorithm may calculate the secondary effects of each componentin the cement slurry and adjust the relative amounts of each componentto ensure the target parameters are met. User input 420 may specify, forexample, a relatively higher free water requirement for the cementslurry. The predictive cement algorithm may choose to include a cementcomponent that requires less water based on the maps and data to ensurethat the free water requirement specified by user input 420 is met.

Reference is now made to FIG. 5 , illustrating use of a cementcomposition 500. Cement composition 500 may comprise any of thecomponents described herein. Cement composition 500 may be designed, forexample, using reactivity mapping as described herein. Turning now toFIG. 5 , the cement composition 500 may be placed into a subterraneanformation 505 in accordance with example systems, methods and cementcompositions. As illustrated, a wellbore 510 may be drilled into thesubterranean formation 505. While wellbore 510 is shown extendinggenerally vertically into the subterranean formation 505, the principlesdescribed herein are also applicable to wellbores that extend at anangle through the subterranean formation 505, such as horizontal andslanted wellbores. As illustrated, the wellbore 510 comprises walls 515.In the illustration, a surface casing 520 has been inserted into thewellbore 510. The surface casing 520 may be cemented to the walls 515 ofthe wellbore 510 by cement sheath 525. In the illustration, one or moreadditional conduits (e.g., intermediate casing, production casing,liners, etc.), shown here as casing 530 may also be disposed in thewellbore 510. As illustrated, there is a wellbore annulus 535 formedbetween the casing 530 and the walls 515 of the wellbore 510 and/or thesurface casing 520. One or more centralizers 540 may be attached to thecasing 530, for example, to centralize the casing 530 in the wellbore510 prior to and during the cementing operation.

With continued reference to FIG. 5 , the cement composition 500 may bepumped down the interior of the casing 530. The cement composition 500may be allowed to flow down the interior of the casing 530 through thecasing shoe 545 at the bottom of the casing 530 and up around the casing530 into the wellbore annulus 535. The cement composition 500 may beallowed to set in the wellbore annulus 535, for example, to form acement sheath that supports and positions the casing 530 in the wellbore510. While not illustrated, other techniques may also be utilized forintroduction of the cement composition 500. By way of example, reversecirculation techniques may be used that include introducing the cementcomposition 500 into the subterranean formation 505 by way of thewellbore annulus 535 instead of through the casing 530. As it isintroduced, the cement composition 500 may displace other fluids 550,such as drilling fluids and/or spacer fluids that may be present in theinterior of the casing 530 and/or the wellbore annulus 535. While notillustrated, at least a portion of the displaced fluids 550 may exit thewellbore annulus 535 via a flow line and be deposited, for example, inone or more retention pits. A bottom plug 355 may be introduced into thewellbore 510 ahead of the cement composition 500, for example, toseparate the cement composition 500 from the fluids 550 that may beinside the casing 530 prior to cementing. After the bottom plug 555reaches the landing collar 580, a diaphragm or other suitable deviceshould rupture to allow the cement composition 500 through the bottomplug 555. The bottom plug 555 is shown on the landing collar 580. In theillustration, a top plug 560 may be introduced into the wellbore 510behind the cement composition 500. The top plug 360 may separate thecement composition 500 from a displacement fluid 565 and also push thecement composition 500 through the bottom plug 555.

The disclosed cement compositions and associated methods may directly orindirectly affect any pumping systems, which representatively includesany conduits, pipelines, trucks, tubulars, and/or pipes which may becoupled to the pump and/or any pumping systems and may be used tofluidically convey the cement compositions downhole, any pumps,compressors, or motors (e.g., topside or downhole) used to drive thecement compositions into motion, any valves or related joints used toregulate the pressure or flow rate of the cement compositions, and anysensors (i.e., pressure, temperature, flow rate, etc.), gauges, and/orcombinations thereof, and the like. The cement compositions may alsodirectly or indirectly affect any mixing hoppers and retention pits andtheir assorted variations.

EXAMPLES Example 1

A Young's modulus test was prepared for 19 cement compositions. Eachcomposition had a density ranging from 9 ppg (pounds per gallon) (1.078kg/L) to 15.8 ppg (1.893 kg/L) with a curing temperature ranging from60° F. (15.56° C.) to 238° F. (114.4° C.). Each of the compositions wasplaced into a cylinder and allowed to cure before being tested in anunconfined compressive strength test to find the Young's modulus of eachset composition. The results are illustrated in FIG. 6 .

A curve was fit to the data gathered in FIG. 6 . It was found that forthe particular compositions tested and plotted the following parameterswere found for Equation 16.

-   -   Aym=275    -   Bden=1.25    -   Bcs=0.63        Where the final model is YM=275(ρ)^(1.25)(CS)^(0.63). It was        observed that the coefficient of determination (r²) for the        particular data was 0.9344.

Example 2

A second Young Modulus test was prepared for 23 cement compositions.Each composition included at least 2 components selected from class HPortland cement, class C fly ash, and pumice in varying concentrations.Each of the cement compositions had a density ranging from 12 ppg (1.438kg/L) to 14.5 ppg (1.737 kg/L) with curing temperatures ranging from100° F. (37.78° C.) to 180° F. (82.2° C.). Each of the compositions wasplaced into a cylinder and allowed to cure before being tested in anunconfined compressive strength test to find the Young's modulus of eachset composition. The results are illustrated in FIG. 7 .

A curve was fit to the data gathered in FIG. 7 . It was found that forthe particular compositions tested and plotted the following parameterswere found for Equation 17.

-   -   Aym=56.7    -   Bden=2.09    -   Bcs=0.56        Where the final model is YM=56.7(ρ)^(2.09)(CS)^(0.56). It was        observed that the coefficient of determination (r²) for the        particular data was 0.9621.

It should be understood that the compositions and methods are describedin terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps.Moreover, the indefinite articles “a” or “an,” as used in the claims,are defined herein to mean one or more than one of the element that itintroduces.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as, rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited, in the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, whenever a numerical range with alower limit and an upper limit is disclosed, any number and any includedrange falling within the range are specifically disclosed. Inparticular, every range of values (of the form, “from about a to aboutb,” or, equivalently, “from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to setforth every number and range encompassed within the broader range ofvalues even if not explicitly recited. Thus, every point or individualvalue may serve as its own lower or upper limit combined with any otherpoint or individual value or any other lower or upper limit, to recite arange not explicitly recited.

Therefore, the present disclosure is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular examples disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Although individual examples arediscussed, the invention covers all combinations of all those examples.Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below.Also, the terms in the claims have their plain, ordinary meaning unlessotherwise explicitly and clearly defined by the patentee. It istherefore evident that the particular illustrative examples disclosedabove may be altered or modified and all such variations are consideredwithin the scope and spirit of the present invention. If there is anyconflict in the usages of a word or term in this specification and oneor more patent(s) or other documents that may be incorporated herein byreference, the definitions that are consistent with this specificationshould be adopted.

What is claimed is:
 1. A method of designing a cement for use in awellbore comprising: obtaining a target Young's modulus and a density;calculating a compressive strength requirement using the target Young'smodulus and the density as an input; classifying a plurality of solidparticulates based on physicochemical properties of the solidparticulates, wherein the solid particulates are classified by an oxideanalysis and a water requirement analysis; calculating a reactive indexfor at least two of the solid particulates; designing a cementcomposition by selecting two or more solid particulates from theplurality of the solid particulates, wherein the designed cementcomposition meets the calculated compressive strength requirement;testing the designed cement composition for compressive strength andYoung's modulus; and confirming the designed cement composition meets orexceeds the Young's modulus target.
 2. The method of claim 1 wherein thecorrelation comprising compressive strength, Young's modulus, anddensity is YM=A_(ym)*ƒ (p)*g(CS) where YM is Young's modulus, ƒ(p) is afunction with density as an input, and g(CS) is a function withcompressive strength as an input.
 3. The method of claim 1 furthercomprising adjusting the cement composition to meet one or more desiredparameters.
 4. The method of claim 3 wherein the one or more desiredparameters comprise a cost objective.
 5. The method of claim 3 whereinthe one or more desired parameters comprise at least one parameterselected from the group consisting of compressive strength, fluid loss,mud densities, slurry density, pore pressures, thickening time, tensilestrength, Young's Modulus, Poisson's Ratio, rheological properties,slurry stability, fracture gradient, remaining well capacity, transitiontime, free fluid, gel strength, and combinations thereof.
 6. The methodof claim 1 further comprising analyzing the two or more solidparticulates of the cement composition to generate data about physicaland chemical properties of the solid particulates and generatingcorrelations between the solid particulates based on the data, thecorrelations being used for classification.
 7. The method of claim 6wherein the analyzing the solid particulates comprises analysis by oneor more techniques selected from the group consisting of microscopy,spectroscopy, x-ray diffraction, x-ray fluorescence, particle sizeanalysis, scanning electron microscopy, energy-dispersive X-rayspectroscopy, surface area, specific gravity analysis, thermogravimetricanalysis, morphology analysis, infrared spectroscopy,ultraviolet-visible spectroscopy, mass spectroscopy, secondary ion massspectrometry, electron energy mass spectrometry, dispersive x-rayspectroscopy, auger electron spectroscopy, inductively coupled plasmaanalysis, thermal ionization mass spectroscopy, glow discharge massspectroscopy x-ray photoelectron spectroscopy, mechanical propertytesting, Young's Modulus testing, rheological properties, Poisson'sRatio, API testing, and combinations thereof.
 8. The method of claim 6further comprising generating a statistical table comprising two or moredifferent parameters of the solid particulates.
 9. The method of claim 8wherein the different parameters comprise a water requirement and thereactive index.
 10. The method of claim 1 further comprising introducinga wellbore treatment fluid into the wellbore, wherein the wellboretreatment fluid comprises the cement composition.
 11. The method ofclaim 1 wherein the cement for use in a wellbore is introduced into thewellbore using one or more pumps.
 12. The method of claim 1 furthercomprising mixing components of the cement for use in a wellbore usingmixing equipment.
 13. A method comprising: calculating a compressivestrength requirement using a target Young's modulus as an input in amodel that is a function of three constants for a given family ofcementitious formulations, density and Young's modulus; selecting atarget reactive index for a wellbore treatment fluid based on thecompressive strength requirement; classifying one or more solidparticulates with an oxide analysis and a water requirement analysis;generating a first design of the wellbore treatment fluid based on thetarget reactive index; testing the first design of the wellboretreatment fluid to obtain a first compressive strength and a firstYoung's modulus; testing two or more additional designs of the wellboretreatment fluid to obtain additional compressive strength values andadditional Young's modulus values; applying regression analysis to thefirst compressive strength, the additional compressive strength values,the first Young's modulus, and the additional Young's modulus to obtainan updated value for the at least one constant; calculating a secondcompressive strength requirement using the target Young's modulus as aninput in the correlation between compressive strength and Young'smodulus, the correlation having the updated value for the at least oneconstant; selecting a second target reactive index for the wellboretreatment fluid based on the second compressive strength requirement;generating an updated design of the wellbore treatment fluid based onthe second target reactive index.
 14. The method of claim 13 wherein thecorrelation is YM=A_(ym)*ƒ (p)*g(CS) where YM is Young's modulus, ƒ(p)is a function with density as an input, and g(CS) is a function withcompressive strength as an input.
 15. The method of claim 13 wherein thetarget reactive index is calculated at a bottom hole circulatingtemperature.
 16. The method of claim 13 wherein the updated design forthe wellbore treatment fluid comprises at least one additive selectedfrom the group consisting of weighting agents, retarders, accelerators,activators, gas control additives, lightweight additives, gas-generatingadditives, mechanical-property-enhancing additives, lost-circulationmaterials, filtration-control additives, fluid-loss-control additives,defoaming agents, foaming agents, transition time modifiers,dispersants, thixotropic additives, suspending agents, and combinationsthereof.
 17. The method of claim 13 further comprising calculating acost of the wellbore treatment fluid.
 18. A system for generating awellbore treatment fluid comprising: a model correlation betweencompressive strength requirement, Young's modulus requirement, anddensity requirement, the model correlation being dependent on threeconstants for a given family of cementitious formulation, density andYoung's modulus; a plurality of solid particulates; and a computersystem operable to accept a target Young's modulus input and densityfrom a user and generate a virtual design of the wellbore treatmentfluid using the target Young's modulus and density input to the modelcorrelation, wherein the wellbore treatment fluid comprises at least twosolid particulates selected from the plurality of solid particulates,wherein the at least two solid particulates are categorized by at leastan oxide analysis and a water requirement analysis, and wherein aconcentration of each of the at least two solid particulates is based ona target property.
 19. The method of claim 13 wherein the correlation isYM=A_(ym)*ƒ (p)*g(CS) where YM is Young's modulus, ƒ(p) is a functionwith density as an input, and g(CS) is a function with compressivestrength as an input.
 20. The system of claim 18 wherein the computersystem is further operable to improve the wellbore treatment fluid bycalculating a reactive index and adjusting a relative amount of each ofthe solid particulates to meet or exceed the target property.
 21. Thesystem of claim 18 further comprising a database, wherein the databasecomprises the solid particulates, a cost corresponding to each of thesolid particulates, a water requirement for each component, and areactive index for each component.
 22. The system of claim 21 whereinthe reactive index is defined by a user or automatically selected by thecomputer system.
 23. The system of claim 18 wherein the computer systemis configured to select an additive to include in the wellbore treatmentfluid, wherein the additive comprises at least one additive selectedfrom the group consisting of weighting agents, retarders, accelerators,activators, gas control additives, lightweight additives, gas-generatingadditives, mechanical-property-enhancing additives, lost-circulationmaterials, filtration-control additives, fluid-loss-control additives,defoaming agents, foaming agents, transition time modifiers,dispersants, thixotropic additives, suspending agents, and combinationsthereof.
 24. The system of claim 18 wherein the computer system isfurther operable to select the solid particulates based on a waterrequirement.